Always focus on the top of the screen. Just before a block falls, a triangular caution sign will appear in the row where it will drop. Use this to always see what is appearing next. Take the high ground and stay on it until you are forced to move. It requires more time to move from lower ground to higher ground than the opposite. You can take advantage on the high ground, especially immediately after a block has dropped. A block almost never drops in the same space twice in a row.